Nuclear power plants in the age of terrorism: Safer than many
think
By Gerald E. Marsh and George S. Stanford
web posted November 19, 2001
Anxiety over a potential terrorist attack on a nuclear power plant
has been frequently expressed in recent days. But is this source
of abundant, environmentally-friendly energy an attractive target
for terrorists?
Not really.
The greatest danger could well be panic caused by
sensationalized reporting, not radiation.
Let's look at the worst terrorists could do.
The crash of a large airliner into a reactor is on everyone's mind.
A reasonable speculation is that a direct hit by one of the heavy
engines (requiring incredibly precise aiming by the pilot) could
split the nuclear plant's reinforced concrete containment. (The
rest of an aircraft is very soft, and would splatter like an egg.)
However, merely cracking the containment would not inflict
serious damage inside. To do that, either the engine must fall in
(instead of being deflected), or enough jet fuel would have to
spill in to burn in a serious fire. Even then, the heavy steel reactor
pressure vessel would probably be undamaged, because it is
surrounded and protected by thick concrete radiation shielding.
The only way that much radioactivity could be spread is if a
steam explosion were to occur. The only conceivable causes
could be either a runaway overpower or complete loss of
cooling. We know of no credible way that the crashing airliner
could cause an overpower. The worst that could be expected is
what is known as a "blowdown," where a main cooling-water
pipe is ruptured by the falling aircraft engine, and the pressurized
water turns to steam. Under these circumstances, the chain
reaction would simply shut down.
However, if the emergency core-cooling system was also
disrupted, the ability to cool the core of the shut-down reactor
could be lost. While a steam explosion in a current power
reactor resulting from complete loss of cooling cannot be
theoretically ruled out, it is no longer considered realistic by the
Nuclear Regulatory Commission - even when evaluating "worst
case" scenarios.
We can forget about steam explosions.
What could happen, if an engine fell in and all cooling were lost?
Some of the fuel would probably melt. After a few hours it might
work through the reactor vessel, spread out and solidify down
below. Some fraction of the more volatile radioactive material
might escape to the atmosphere. However, with a timely,
temporary evacuation, in accordance with the site's emergency
plan, no serious off-site exposure to radiation should occur.
There are two other potential targets at a typical reactor site:
spent fuel in dry storage and in wet storage. The dry-storage
casks are made of concrete or thick steel. If directly hit by a
jetliner, a few of them might break, but the ensuing fire could not
disperse a large amount of radioactivity. Nevertheless,
temporary local evacuation might be called for.
The storage pools used for fresher spent fuel are somewhat more
vulnerable, although they are not pushovers. Nonetheless, a
jetliner considerably smaller than a 767 might be sufficient to
disrupt one. This alone might make the pool a more attractive
target than the reactor itself.
So nuclear plants are low-payoff targets.
There is a way to virtually eliminate the damage potential of the
storage pools: the Yucca Mountain repository in New Mexico
should promptly be opened as an interim storage facility, and the
spent fuel currently in pools beside reactors should be moved to
storage pools in this secure, underground location.
Transportation in "wet" casks would be a very low-risk
operation, although probably there are not now enough casks to
allow a complete, expeditious transfer. Thus some hardening of
the storage pools might be wise, and as much fuel as possible
should be in the less-vulnerable dry-storage type of cask.
Yucca Mountain should be considered an interim storage facility
because reprocessing spent reactor fuel should be reconsidered
in light of new, proliferation-resistant technologies. Re-using
spent fuel in fast reactors is very attractive - what otherwise
would need to be stored for ten thousand years is now
consumable fuel, and the residual waste is harmless in 500 years.
Given the instability near the Persian Gulf and the fragility of the
Saudi monarchy, oil shipments could soon be disrupted. The less
we depend on this oil the better. In the long run, fossil fuels are
limited - nuclear power is not. We should not allow uncalled-for
panic, politics, or political correctness to curtail the safe use of
nuclear power.
Gerald Marsh is a physicist who served with the U.S. START
delegation and was a consultant to the Office of the Chief of
Naval Operations on strategic nuclear policy and technology for
many years. George Stanford is a nuclear reactor physicist, now
retired from Argonne National Laboratory after a career of
experimental work pertaining to power-reactor safety. Courtesy
of the The National Center for Public Policy Research (http:
//www.nationalcenter.org).
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